Improved treatment of the CRS difference equation for the quenched dilute random bond Ising model

The theory of Frank and Jan (1979) for the quenched dilute bond Ising model, which predicts good reduced-temperature critical curves, is generalised to predict good critical curves for the non-reduced temperature. This is done by adapting the set of critical correlation function approximations of Frank and Mitran (1977, 1978) to the random case. The non-reduced critical curves are far closer to Rapaport's series (1972) results than those of either Frank and Jan or Tahir-Kheli and Elliott (1977) for concentration of connected bonds x>or approximately=0.4.